Fire-control apparatus particularly intended for naval guns



H. SUNDHAU'SSEN.

FIRE CONTROL APPARATUS PARTICULARLY INTENDED FOR NAVAL GUNS.

APPLICATION FILED sums. 1920.

1,3?5,264, Patented Apr. 19, 1921.

4 SHEETSSHEET I.

H. SUNDHAUSSEN.-

FIRE CONTROL APPARATUS PARTICULARLY INTENDED FOR NAVAL GUNS. APPLICATION FILED SEPT.3| 1920.

1,375,264. Patented Apr. 19, 1921.

4 SHEETSSHEET 2.

d/mm md H. SUNDHAUSSEN.

FIRE CONTROL APPARATUS PARTICULARLY INTENDED FOR NAVAL GUNS.

APPLICATION FILED SEPT. 3. 1920.

1,375,264. A Patented Apr. 19, 1921.

4 SHEETS-SHEET 3.

mxm/mm 1 V H. SUNDHAUSSEN.

FIRE CONTROL APPARATUS PARTICULARLY INTENDED 'FOR NAVAL GUNS.

nmmmm APPLICATION FILED SEPT.3, 1920- Patented Apr. 19, 1921.

4 SHEETS-SHEET 4.

UNITED STATES PATENT OFFICE.

HERMANN SUNDHAUSSEN, OF ESSEN, GERMANY, ASSIGNOB 1'0 FRIED. KRUPP AKTIENGESELLSCHAFT, OF ESSEN-ON-THE-RUHR, GERMANY.

FIRE-CONTROL APPARATUS PARTICULARLY INTENDED FOR NAVAL GUNS.

Specification of Letters Patent. Patented Apr, 19, 1921.

Application filed September 3, 1920. Serial No. 408,090.

T 0 all 20 kom it may concern:

Be it known that I, HERMANN SUND- HAUSSEN, residing at Essen, Germany, a citizen of the German Republic, have invented a certain new and .useful Improvement in Fire-Control Apparatus Particularly Intended for Naval Guns, of'which the following is a specification.

The present invention relates to a fire control apparatus particularly intended for naval guns, and in which a gyroscopic apparatus placed on the gun mounting is directly adjustable according to the indications of the gyroscopic apparatus intended for the bisection of the target or the horizon.

The invention will be described with reference to the accompanying diagrammatic views, in which- Figure 1 shows a construction of the fire control apparatus constituting the subjectmatter of this invention, in which only the construction of the two gyroscopic apparatus is shown, but not the arrangement of the several parts of the apparatus at the observing station and on the gun.

Figs. 2 to 4 eachshow a fire control apparatus forming the subject-matter of thls invention, said figures also illustrating the arrangement of the different parts of the fire control apparatus at the observing sta-" tion and on the gun.

Referring to the construction shown in Fig. 1 A- denotes the gyroscope which'rotates about a vertical axis, and which is suspended by means of a Gardan suspension E in a casin B- which oscillates about a horizontal axis. The Cardan suspension E is mounted in the casing B by means of axes D. This casing B is oscillated about the said horizontal axis by a hand wheel 0, on the shaft of which is mounted a worm C which cooperates with a series of teeth I) on the casing B. On one end of the spindle D, which projects from the casing B which is stabilized by the gyroscope A and coinciding with the axis of oscillation of the said casing, is mounted a sighting telescope D and a downwardly extending pointer (P. This pointer (Z carries a contact piece d which is adapted to travel over a resistance b arranged on the casing B and centric with its axis of oscillation. The

Cardan ring E which serves as a bearing for the gyroscope A, is provided with a vertical sighting rib e, which lies opposite an opening b in the casing, in such a way that, for the purposeof rocking the sighting line about the spindle D, a lateral pressure can be exerted on the sighting rib e. The con- I point where the gyroscopic apparatus A B is mounted, there is provided a second gyroscope G, also capable of rotation about a vertical axis and is suspended by means of a Cardan suspension in a casing H, which can be adjusted about a horizontal axis by means of an apparatus not shown. The construction of the gyroscopic apparatus G, H corresponds exactly to that of the gyroscopic apparatus A, B, and the gyroscopic apparatus G, H, is also rigidly mounted on the end of the spindle J, which projects from the casing H and is adapted to be stabilized by the gyroscope G and coinciding with the axis of oscillation of the casing 'H is mounted the sighting telescope J and a downwardly extending pointer 6 This pointer 2' likewise carries a contact piece i which is adapted to travel over a resistance h concentric with the spindle J. Furthermore, thereis provided in the case of the gyroscopic apparatus G, H, a vertical si hting rib 10 mounted on the Cardan ring which serves as a bearing for the gyroscope G, which rib fulfils the same purpose as the rib e in the gyroscopic a paratus A, B. The gyroscopic apparatus G3, H is provided with two firing tongues 70 M, which are adjustable relatively to each other to correspond with the preliminary ignition angle (the adjusting apparatus is not shown), and of which one tonguelc is mounted on the Cardan ring K, and the other on the casing H of the gyroscope. The two gyroscopic apparatus A, B and G, H are electrically connected together as follows. From the ends of the resistance 6 conductors-M and M lead to two fixed contact pieces m and W, each of which bears against a sector-shaped resistance N h curvature of which coincide with the spindle J, are connected at one end in the manner shown in the drawing, with the two ends of the resistance k by conductors n and a respectively.- The construction of the resistances h and N, N is such that equal central point angles correspond to equal variations in the resistance, so that according to the value of the resistance of the parts of the total resistance M, W, N, a N lying on both sides of the contact piece 2' a fixed value for a simultaneous and uniform rotation of the casing H and the member N is maintained. The contact pieces d and i form, as has been stated, the outlet and inlet of a double branch circuit. Between the two branches of the said circuit is interposed, after the manner of the Vheatstone bridge, a bridge connection m and a. sensitive galvanometer m.

For the explanation of the working of the described apparatus, it will be assumed that the two gvroscopes A and G are running, and that the casings B and H including the member N assume such a position, that when the two telescopes D and J are adjusted horizontally by pressure upon side ribs 0 and 7c, the contact pieces 03 ,71 and the contact pieces m m are opposite the center of the resistances 6 h and N, N In this position of the parts, the values of the resistances lying on both sides of the contact pieces d and 2' stand at the same ratio, and the bridge connection m and the galvanometer m is therefore devoid of current. If now for example, the telescope D and with it the contact piece (Z makes any rotary movement about the shaft D, the ratio of the resistance values above mentioned varies, and there consequently flows in the bridge connection m a current which causes the pointer of the galvanometer m to swing in one direction or the other. The gun layer who operates the gyroscopic apparatus G, H and watches the galvanometer m, then exerts a correspondingly directed lateral pressure on the sighting rib and thereby causes the telescope J to execute a rotary movement similar in direction to the direction of rotation of the telescope D The pressure on the sighting rib is is continued until the contact piece 2' which takes part-in the rotary movement of the telescope J has reached a point on the corresponding resistance M, at which the ratio of the resistance values mentioned above is again equal, and at which the current in the bridge connection m consequently ceases to flow so that the pointer of the galvanometer m again resumes its zero position. moment the telescope J assumes a position 1n which its sighting line is again parallel to the sighting line of the telescope D The above described apparatus works in a similar manner when the telescopes D and J are held in a horizontal direction by i the gyroscopes A and G and the casing B is At this rotated by means of the hand wheel 0 In this case a current flows immediately in the bridge connection m, which causes the pointer and the galvanometer m to swing. The gun layer who watches the galvanometer oa then rotates by means of an operating mechanism (not shown) the casing H and the member N 2 conjointly therewith in the corresponding direction, until that point of the resistance H is opposite the contact piece 2' which corresponds to the point of the resistance B which is opposite the contact piece (Z As soon as the, angular position of the casing H accurately corresponds to that of the casing B, the current in the bridge connection m ceases to flow and the pointer of the galvanometer returns to its zero position.

If no change be made in the position of the parts of the galvanometer apparatus shown in the drawing, and if the telescope J also retains its horizontal position under the action of the gyroscope, it is possible, as will be shown hereafter, to rotate by means of the operating mechanism already mentioned (but not shown) the casing H and the member N conjointly therewith without any current flowing in the bridge connection m and without any movement of the pointer of the galvanometer. As can be seen, particularly at the lower part of Fig. 1, the part of the resistance h lying on one side or the other of the contact piece 2' will, on the conjoint and uniform rotation of the easing H and the member N be diminished or increased by the. same amount as that part of the resistance wire and N which lies on the same side and reaches to the contact pieces m and m is augmented or diminished. The ratio of the active resistances on both sides of the circuit closing piece i retain, therefore, during the conjoint rotation-of the casing H and the member N their original value, and consequently no current can flow in the bridge connection we.

The above described apparatus therefore enables, the angular position of a sightircig telescope J stabilizable by a gyrosco 3e to be held in respect to its casing I- permanently in agreement with the angular position which the sighting telescope D placed at a distant point and likewise stabilizable by means of gyroscope A, assumes in respect to its corresponding casing B. It insures, however, also a possibility of altering the angular position of the casing H which belongs to the sighting telescope to be held in agreement, without this alteration being made noticeable on the indicating apparatus at which determines the adjustment of the sighting telescope which is to be pointed.

Referring to the construction shown in Fig. 2 the application of an apparatus according to Fig. 1, to a fire control apparatus for naval guns is shown, in which the part marked I is placed on an elevated observing station for example, and the part marked II on the gun mounting. At the observing station is placed a cyllndrical pedestal P, provided with a traverse circle 12 which is pivotally mounted a conicallyshaped cap P provided with a reading-0E mark p and said cap P being adapted to rotate about a vertical axis. On this cap P a horizontal arm p is mounted to oscillate about a horizontal axis, and carries on its free end the bearing with a gyroscope casing B of a gyroscope (not shown), which os'cillatesabout a vertical axis. To the arm 19 is rigidly connected a downwardly extending worm wheel sector 1), with the worm teeth of which, a worm which is rotatably mounted on the cap P and provided with a hand wheel 19, engages. The worm shaft is positively connected to two rotating disks, each of which carries a coarse and a fine mark p and 10 respectively, and in respect of which two pointers p and 10 adjusted from a distance and connected with each other on the coarse and fine system, are loosely rotatable. A similar structure is shown in Patent No. 1,123,067 to Barkhaussan and Kaminski. On that end of the stabilized axis which projects fromthe casing B of the gyroscopic apparatus, is rigidly mounted a sighting telescope D and a downwardly extending pointer (1 This pointer d is connected to one pole of a source of current, and carries on its end a contact piece 0Z adapted to travel over a resistance 6 on the casing B and concentric with its axis of oscillation.

From the two ends of the resistance wire 0Z lead two electric conductors M and M to two contact pieces m and m, which are situated on the gun mounting and are rigidly attached to the outside of one wall of the gun carriage M. In the gun carriage is mounted upon two horrizontal trunnions the gun barrel (not shown) and one of said horizontal trunnions, N is shown in the drawing. On the trungm N are arranged two resistances N and N concentric with its axis of oscillation and on which are caused to bear the contact pieces m and m The trunnion N is bored and the axis of such boring coincides with the axis of oscillation of the trunnion N In this boring is mounted to rotate loosely a double lever Q, Q of which one arm Q, carries on its free end a bearing ring g for the casing H of a gyroscope (not shown) which rotates about a vertical axis, while the other arm Q is provided onits free end with a series of worm teeth 9 The double lever Q, Q} is rocked on the axis of the trunnion N by means of a worm R and a hand wheel 1' mounted to rotate in a member a rigidly connected to the trunnion N The Worm and on shaft is positively connected to two disks each carrying a coarse and a fine mark r and r and in respect of which two pointers 1' and 1* adjustable from a distance and connected with each other on the coarse and fine system are adapted to rotate loosely. On the end of the stabilized axis which projects from the casing His rigidly mounted a sighting telescope J and a downwardly extending pointer '5 This pointer i is connected to the one'pole of the source of current and carries on its free end a contact piece 2' which is adapted to travel over a resistance wire h arranged concentrically with its axis of rotation. The ends of the resistance h. are connected in the manner shown in the drawing, to the two adjacent ends of the resistances N and N by conductors n and n Between the two conductors M and M is interposedafter the manner of the Wheatstone bridge, a bridge connection provided with two galvanometers m and m one of which is placed on the gun mounting and the other at the observing station. The gyroscopic apparatus which is mounted on the gun, is also provided with two firing tongues, one of which is arranged in the manner shown in Fig. 1, on a part which can be stabilized by the gyroscope, while the other is arranged on the gyroscope casing.

In the description of the working of the above described fire control apparatus let it be assumed that the two gyroscopes'are in action and that all the parts are in the po-- sition shown in the drawing, that is the relative positions of the two pointers d and i to their casings B and H corres 30nd and the two pointers m and m of t e galvanometers are in their zero positions. Let it be also assumed that throughout the course of the whole of the adjusting operation to be hereafter described, that care be takenby applying pressure suitably to the s1ght1ng rib corresponding to the sighting r1b 6 (see Fig. 1), that the sighting telescope D which is stabilized by means of the gyroscope does not alter its position in space.

If now a target, to which the cap P and also the gun is adjusted sideways, is to be fired at, the pointers 12 10 and r, r are first adjusted from a distance to the range, gun to target, which has been ascertained by measurement for example. The gun layer who observes the target through the telescope D next turns the hand wheel 10 until the marks p and p are oppositev the corresponding pointers p and p During this rotation of the hand wheel 9 the arm 10 which carries the gyroscopic apparatus is rocked aboutits axis of rotation by an angle corresponding to the range gun to target. As during this rotation the sighting telescope D stabilized by the gyroscope and the parallel to itself, a relative rotation takes place between the pointer d and the casing B through an angle which is equal to the posite the pointers r and r By angle of rotation of the arm 10. The pointer d contacts-with its contact piece 05 on the resistance 6 at a poifit which is removed from the previous point of contact, an angular distance equal to the angular displacement of the arm 19*. Another gunner on the mounting also rotates simultaneously with the rotation of the hand wheel 12 the hand wheel 7' until the marks r and r are opthis rotation of the hand wheel 1 the double lever Q Q which carries the gyroscopic apparatus is rocked about the axis of the trunnion through an angle of elevation corresponding to the range, gun to target. Between the sighting telescope J which remains parallel to itself under the action of the gyroscope,

and the pointer i rigidly connected thereto on the one hand and the casing H-on-the other hand there is a relative rotation through an angle which is equal to the angle of rotation of the double lever Q Q. The pointer 2' contacts therefore through its contact i with the resistance 72, at a point which is removed from the previous point of contact, through an angle which is equal to the angle traversed by the compound lever. Q Q}. The an ular movement of the compound lever-Q (5 is equal to that of the arm 39. The

position of-the pointer i in respect to the resistance It therefore corresponds, after making the adjustment above mentioned, exactly to that of the pointer d with respect to the resistance wire 6 and the bridge connection m is therefore devoid of current, and the two pointers of the galvanometers m and m retain their zero positions.

The elevation which corresponds to the range, gun to target, is then imparted to the gun barrel, and for this purpose the gun barrel is rocked by means of its elevating gear through an angle in the direction of the arrow as, about the axis of the trunnions,

which corresponds to the range, gun to target. This rocking movement is taken part inby the resistances mounted on the trunnion N and the member n rigidly connected thereto and also the double lever Q}, Q which carries the gyroscope, the participation of these parts in this motion taking place in the same direction as the gun barrel moves. As during this rocking movement the sighting telescope J which is under the action of the gyroscope and the pointer i rigidly, connected thereto does not alter its position in space, a relativemovement takes place between the pointer i and the resistance 71,1 through an angle which is equal to the angle of elevation imparted to the gun barrel. The portion of the resistance 72, lying on either side of the contact piece '5 will therefore be increased or diminished during the adjustment ofthe elevation of the gun barrel by an amount equal to that by which the active portion of the resistance wires N and N connected to that part is di- "minished-or increased. The ratio of the bridge connection when the adjustment of the elevation of the gun barrel is made. The

brid e connection m will remain devoid of current, and the two pointers of the galvanometers m and m retain their zero positions. 4

As soon as the gun barrel has been adjusted for elevation, a switch (not shown) which is contained in a circuit containing the two firing tongues andthe winding of a firing magnet, is closed and the firing of the gun accordingly follows during the further rolling movement of the ship when the two firing tongues which are set with respect to each other so as to correspond to the angle of preliminary ignition touch each other, c

that is to say, at an instant which lies in the well known way by a period of time corresponding to the angle of preliminary ignition in advance of the passage-of the ship through its central floating position.

As has already been stated at the commencement of this description relating to the working of the apparatus, the sighting telescope directed on the target is prevented during the whole course of the adjusting operations above described from undesired rotations about the horizontal axis stabilized by'the gyroscope, such for example as occur in movements of precision of the gyroscope, by suitable lateral pressure on the sighting rib, so that it takes with certainty a position which is permanently directed on to the target. If the gyroscopic apparatus situated at the gun mounting causes an undesired rotation of the sighting telescope stabilized by the gyroscope, which in the case of a target shrouded in smoke would not be at once recognizable by the sighting telescope J the pointer i rigidly connected to the sighting telescope J at once takes a position with respect to the corresponding resistance k which no longer corresponds to the position of the pointer d with respect to the resistance 6 The conditions of re sistance in the Wheatstone bridge are accordingly so altered that a current flows in the bridge connection m which causes both the galvanometers to swing. The gunner whose duty it is to work the sighting rib of the gyroscopic apparatus situated at the gun mounting must in this case exert a correspondingly directed lateral pressure on the sighting rib untilthe bridge connection m is again devoid of current and the two galvanometers return to their zero positions At this instant the position of the pointer 71 again corresponds with that of the pointer '03 and the sighting telescope J again assumes a position which is directed on the sighting telescope D meets a point of the horizon which is free from smoke or fog. The sighting telescope is then directed on to the horizon by suitable lateral pressure on the sighting rib. No change is thereby made in the method of operation of the gyroscopic apparatus situated at the gun mounting.

In the modified construction of a fire control apparatus shown in Fig.- 3 the part of a the apparatus situated at the observing station marked I is similar to the corresponding part of the apparatus shown in Fig. Q-but in the case of the part marked II at the gun mounting the casing of the gyroscope H is mounted on a bearing ring a which is rigidly attached to one of the trun- 'nions N of the gun and the arrangement is so devised that the horizontal spindle J (not shown) stabilized by the gyroscope coincides with the axis of the trunnions. On the end of the spindle which projects from the I two ends of-the resistance are connected in the manner shown in the drawing to the two adjacentends of two resistances N and N also running concentric with the axis J 4 and arranged on the trunnion N against conductors M and which two contact pieces m and m mounted on the wall of the Igun carriage hear. The

l 1 leading from these two contact pieces m and m are taken in a manner corresponding similar to the construction shown in Fig. 2, to the two ends of a resistance Z2 arranged on the casing B of the gyroscope over/which the contact piece 03 mounted on the stabilized axls D and connected to one pole of the source of 7 current is adapted to travel. There is also interposed in a manner similar to the con-' struction shown in Fig.2 betweenthe two conductors according to the manner of the Wheatstone bridge abridge connection m containing two galvanometers m* and m".

In the description of the Working of the fire control apparatus shown in Fig. 3 the operation will aain be 'described from the adjustment of t 10 various parts shown in the drawing in which the sighting line of the sighting telescope D directed on the tarand the two get lies horizontal and in which the pointer 2 of thegyroscopic apparatus mounted on the gun assumes when the gun barrel is directed horizontally a position which corresponds to the pointer 03 The bridge connection m is therefore devoid of current, galvanometers are in-their zero positions. r

When firmg at a target, the arm which carries the g roscopic apparatus is adjusted nitu e of which is determined by the angle of elevation which has been adjusted. The polnter 03 contacts therefore through its contact piece d with resistance 6 ate, point which is removed from the previous point of contact through an angle which is equal to the an le through which the arm p is moved. s during this adjusting operation no change has taken place in the mutual position of the parts of the gyroscopic apparatus on the gun mounting, a disturbance in the state of equilibrium of the Wheatstone bridge takes place, and the bridge connection m receives a current. The two pointers of the galvanometers therefore swing. The pointer 71 of the gyroscopic apparatus situated at the gun mounting is therefore rotated by suitable pressure on the sighting rib (k in Fig. 1) about the axis of the spindle J until the pointer i assumes a position with respect to the resistance k which corresponds to the position of the pointer 03 with respect to the resistance wire b As soon as this is the case the pointers of the two galvanometers m, and m a ain return to their zero positions. IFinal y the gun barrel (not shown in the drawings) is adjusted by means of the elevating gear to the angle of elevation which corresponds to the range of the target. The resistances N and N mounted on the trun-' nion N and also the resistance 7: on the casing of the gyroscope also take part 'in the elevation movement ofthe gun barrel, while the pointerz' retains in space-the angular position imparted to it'by the gyroscope. No change occurs therefore in the ratio of the resistance which is active on both sides of the contact piece i by the elevation movement of the gun barrel and the pointers of the g'alvanometers accordingly retain their zero positions. As soon as the adjustment of the elevation of the gun barrel has been completed, the. n is fired automatically in 'a manner whic corresponds exactly with the manner described for the construction illustrated by Fig. 2.

The constructlon shown in Fig. tdifiers from the construction shown in Fig. 2 by the fact that the casing of the gyroscopic apparatus situated at the observlng station and which forms the bearing member is attached to the cap P itself and that the resistance N and N provided at the gun, mounting are not mounted on the trunnion N but on the double lever Q Q, which is adjustable about the axis of the trunnions to correspond to the angle of elevation and carries the gyroscopic apparatus.

In the working of the fire control apparatus shown in Flg. a only the angle of the target but not the angle corresponding to the angle of range of the target will be adjusted on the gyroscopic apparatus situated at the gun mounting and it is necessary to a gun layers. 3 5' take care at the gyroscopic apparatus situated at the gun mountin by applying suitable pressure to the sig ting 1% that the pointers of the galvanometers retain their central positions.

All the construction of the fire control apparatus which form the subject matter of this invention insure in addition to simple and great accuracy of adjustment and ease of manipulation of the apparatus, the advantage that the adjustment and firing of the guns fitted with an automatic gyroscopic firing apparatus, can also be carried out when the ship passes through the central floating position and when the target is only transitorily or permanently invisible to the The construction and ease of manipulation of the apparatus which insures the simplicity and great accuracy of adjustment is due to the fact that the gyroscopic firin apparatus mounted on the gun is adjustable directly according to the indications of a gyroscopic apparatus intended to coincide with the target or the horizon and consequently any divergences of thesighting line of the gyroscopic apparatus situated at the observing station are recog-.

nizable at once and can be avoided. It is further due to the fact that with the above described selection of the electrical system of transmission unavoidable fluctuation of tensionon the mains have no efiect on the adjustment of the pointers of the galvanometers and consequently cannot give rise to any incorrect adjustments and it is clear without any further explanation that the galvanometer pointers retain their zero positi'ons independently of the tension of the mains aS long as the bridge connection is devoid of current. A further advantage of the subject matter of the present invention is that it is possible for the gunner who marks the horizon at the observing station at any time when the target is obscured, to

rock the gyroscopic aplparatus about its vertical axis on the cap .3, until it is able to mark a point on the horizon winch is not obsoured and that the fire control apparatus when the range of the target and the traverse are known. I

In the fire control apparatus shown in Fig. 4 any possible errors in adjustment are reduced to a minimum, as in this form, the adjustment of the sighting telescope to the angle of elevation corresponding to the range of the target which 1s otherwise necessary on the gun mounting is omitted and only the adjustment of the gyroscope by lateral pressure on the sighting rib need be carried out on the gun mounting.

The fire control apparatus shown in Fig. 3 enables, when several guns are simultaneously adjusted from an observing station a particularly good agreement of their adjustment. I

Claims. 1. An apparatus of the class described comprising a stabilizing apparatus, a device stabilizable by said apparatus, a second stabilizing apparatus, a second device stabilizable by said apparatus, means for adjusting the stabilizable devices, electric means connecting said stabilizing apparatus and stabilizable devices in such a manner that the one stabilizable device is adjustable parallel to the other stabilizable device.

ing device, a second sighting evice, a sec- 3 'ond 'stablhzing apparatus for said second sighting device, a two part electric circuit connecting said stabilizing apparatus, re-

sistance elements interposed in said circuit, means controlled by the position of the sighting device for varying the degree of resistance included in each part of the two part circuit, a galvanometer controlled indicator in said clrcuit and means for adjust ing the sighting device.

4. An apparatus of the class described which comprises a stabilizing device, 9. casing therefor, a sighting means controlled by the stabilizing device, a second stabilizing device and casin therefor, a si hting means controlled by said stabilizing device, resistanqe elements mounted u on said casings, osclllatorv contacts carrie by the sighting means, additional resistance elements rotatable with the gun, a two part circuit including the oscillatory contacts and resistance elements, relative movement between said oscillatory contacts and the first mentioned resistance elements causing a variation in the degree of resistance in one part of the two part circuit, said additional resistance elements compensating for any further relative movement between one oscillatory contact and resistance element.

5. An apparatus of the class described which comprises a sighting device, means for stabilizing said sighting device, means for laterally adjusting the sighting device,

means for adjusting the sighting device to the range of the target, a second sighting device, means for stabilizing said second sighting device, means pivotally supporting said second sighting device and for adjusting it to the range of the target, a two part circuit including galvanometer indicators, resistance elements mounted adjacent to said sighting devices and included in said circuit, means carried by said sighting device for varying the resistance in either part of the two part circuit and additional resistance elements operatively connected to a movable portion of the gun for compensating for one portion of the variable resistance. f

6. An apparatus of the class described which comprises a sighting telescope, means for stabilizing said sighting telescope, a ro tating support for said sighting telescope to allow for lateral adjustment, a pivotally mounted arm supporting said telescope to allow it to be adjusted to the range of the target, a second sighting telescope, means for stabilizing said second telescope, said second telescopebeing fixed to a part which takes part in the rotary movement of the gun and electrical means connectin said sighting telescopes for indicating their different relative positions.

7. An apparatus of the class described which comprises a sighting device, means for stabilizing said sighting device, a rotary support for said sighting device, a second sighting device, means for stabilizing said second sighting device, a pivotally mounted arm for supporting said second sighting device, said arm being mounted on a portion of the gun which takes part in the elevating movement thereof, electrical means connecting the sighting devices for indicating their relative positions and additional electrical means for compensating for part of the movement for one of the sighting devices.

The foregoing specification signed at Essen, Germany, this 16th day of June, 1920.

HERMANN SUNDHAUSSEN.

In presence of- HANS GoTTsMANN, J OHANN DEOKERS. 

